... Department of Human Genetics Division of Medical Genetics www. g e n etics.emory.edu The Genetics of Blood Type ©2006 Blood type is an example of a trait determined by a single gene. Each of ... properties of an organism that are produced by the interaction of the genotype and the environment. In this case, the A, B, O allele combination a person has is their genotype, while their blood type ... along with the O gene, the A or B gene determines the person’s blood type. A person is type O only if he/she inherits two O genes.Depending upon parental blood types, a variety of blood type combinations...